Thermal tuft fluid flow investigation apparatus with a color alterable thermally responsive liquid crystal layer

Abstract

A heat transfer-based surface flow visualization method and device that uses a temperature sensitive material to detect advection along a substrate upon application of heat and air flow and thereby provides a surface flow pattern. The present invention includes the capability of providing surface flow patterns for positions of flow separation, reversal of flow and transition flow and is non-intrusive and more cost effective than known methods.

What is claimed is: 
     
       1. Laser based thermal tuft fluid flow investigation apparatus comprising the combination of: a substrate member comprising a shape-similar thermally insulating model of a workpiece subjected to said fluid flow;   a porous optically opaque coating layer received on said substrate member;   a color-alterable thermally responsive coating layer received on said substrate member porous optically opaque coating layer in thermal communication with said fluid flow;   laser apparatus optically coupled with a selected fluid flow-subjected local area portion of said color alterable thermally responsive coating layer; and   video electronic apparatus also optically coupled with said selected fluid flow-subjected local area portion of said coating layer and responsive to both fluid flow related coating layer color changes and coating layer illuminated-spot shape distortion changes induced by changes in said fluid flow.   
     
     
       2. The laser based thermal tuft fluid flow investigation apparatus of claim 1 wherein said substrate member comprises a life-sized model of a workpiece subjected to said fluid flow. 
     
     
       3. The laser based thermal tuft fluid flow investigation apparatus of claim 1 wherein said substrate member is selected from the group consisting of methyl acrylate plastic and polystyrene foam. 
     
     
       4. The laser based thermal tuft fluid flow investigation apparatus of claim 1 wherein said porous optically opaque coating layer received on said substrate member comprises black paint. 
     
     
       5. The laser based thermal tuft fluid flow investigation apparatus of claim 1 wherein said color-alterable thermally responsive coating layer received on said substrate member porous optically opaque coating layer in thermal communication with said fluid flow is selected from the group consisting of thermal liquid crystals and phosphor. 
     
     
       6. The laser based thermal tuft fluid flow investigation apparatus of claim 1 wherein said laser apparatus optically coupled with a selected fluid flow-subjected local area portion of said color alterable thermally responsive coating layer comprises an ADLAS diode pumped YAG laser. 
     
     
       7. A non-intrusive, heat transfer-based surface flow visualization method comprising the steps of: coating an opaque substrate with phosphor;   heating said phosphor;   conducting and conveying said heat along said substrate by applying air flow thereto; and   observing a directional flow pattern within said phosphor on said substrate.   
     
     
       8. A non-intrusive, laser based thermal tuft fluid flow investigation method comprising the steps of: coating a shape-similar thermally insulating model of a workpiece having a first porous, optically opaque coating layer thereon with a second color-alterable thermally responsive coating layer;   laser-induced heating of a selected flow-subjected local area portion of said second color-alterable thermally responsive coating layer; and   videotaping said selected flow-subjected local area portion of said second color-alterable thermally responsive coating layer, said videotaping responsive to both fluid flow related coating layer color changes and coating layer illuminated-spot shape distortion changes induced by changes in said fluid flow.   
     
     
       9. The non-intrusive, laser based thermal tuft fluid flow investigation method of claim 8 wherein said shape-similar thermally insulating model of a workpiece is selected from the group consisting of methyl acrylate plastic and polystyrene foam. 
     
     
       10. The non-intrusive, laser based thermal tuft fluid flow investigation method of claim 8 wherein said second color-alterable thermally responsive coating layer is selected from the group consisting of liquid crystals and phosphor. 
     
     
       11. The non-intrusive, laser based thermal tuft fluid flow investigation method of claim 8 wherein said shape-similar thermally insulating model of a workpiece has a thermal conductivity of less than 0.4 British Thermal Units. 
     
     
       12. The non-intrusive, laser based thermal tuft fluid flow investigation method of claim 8 wherein said coating layer illuminated-spot shape distortion change is a tear-drop pattern which points in the direction of flow.